This invention relates to the field of surface catalytic reactions and/or heat exchange. The present invention provides a reactor (sometimes referred to as Stackable Structural Reactor or SSR) which fits within a cylindrical tube, and which effectively transfers heat from the tube to the interior of the reactor, or from the interior of the reactor to the tube.
The reactor and improvements thereof of the present invention achieve similar objectives as those of the catalyst supports described in U.S. Pat. App. Pub. Nos. 2007/0025893, 2006/0263278, 2006/0245982, 2006/0245981, 2006/0230613, 2006/0228598, 2006/0019827 and 2006/0008414 and U.S. Pat. Nos. 7,150,099 and 6,920,920, the contents of which are incorporated herein by reference in their entirety.
The reactors shown in the above-cited applications, and others reactors of the prior art, generally occupy substantially all of the space within a cylindrical outer tube. An inherent problem with reactors of this kind is that they do not perform particularly well near the center of the reactor. It has been found that most of the catalytic reactions occur near the outer portions of the reactor, i.e. near the outer tube where heat exchange is more readily available. This problem reduces the capacity of the reactor, effectively limiting the throughput that can be accommodated at the desired level of conversion.
The present invention provides a reactor structure which solves the above problem. The reactor of the present invention will accommodate substantially more throughput than reactors of similar size of the prior art.
Another problem encountered with reactors installed in cylindrical tubes is that of metallic creep and thermal expansion. The reactors described in the above-cited applications, as well as the reactor of the present invention, are intended to be inserted into metallic tubes and sometimes operated at high temperatures (in the range of 850-900° C.) and high pressures (in the range of 20-30 bar). The pressure creates a large hoop stress, which the tube material has difficulty resisting at the high temperature. Over a period of years, creep in the metal outer tube causes the diameter of the tube to grow. Even a few millimeters of growth in the tube diameter creates an undesirable gap between the reactor and the surrounding tube. A typical reactor which has been inserted into a new tube, such that the reactor is initially in good contact with the tube, will lose contact with the tube when the tube creeps over the years. Such creep will cause a significant drop in performance.
The present invention provides structure which avoids the above problem. The invention includes a device that continuously compensates for creep, insuring proper contact between the reactor and the surrounding outer tube.
The reactor of the present invention can be used wherever ceramic packed beds have been traditionally used, for example, in the field of catalytic fuel reforming, to make hydrogen, which is then used in generating electricity through a fuel cell, or in other industrial processes such as oil and gas refining, ammonia and fertilizer production, hydrogenation of oils and chemicals, and iron ore reduction. The reactor could be used as a catalytic or non-catalytic combustor, as a water-gas shift reactor, as a Fischer-Tropsch reactor, or as a simple heat exchanger.